Excited-State Dynamics in Monolayer Black Phosphorus: Exciton Relaxation Modulated by Defects

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Black phosphorus (BP) is a promising 2D material for optoelectronics and solar energy.
• Intrinsic defects in BP can negatively impact device efficiency.
• Understanding defect-induced property modifications is vital for material optimization.

Purpose of the Study:

• To investigate the impact of six distinct defect types on the excited-state dynamics of monolayer black phosphorus.
• To analyze how defect engineering modifies the electronic and excitonic properties of BP.
• To identify specific defect configurations with superior optoelectronic characteristics.

Main Methods:

• Employed static electronic structure calculations.
• Utilized linear-response time-dependent density functional theory (LR-TDDFT) for nonadiabatic dynamics simulations.
• Incorporated excitonic effects explicitly into the simulations.

Main Results:

• Defect engineering in BP significantly alters ground-state properties (e.g., density of states) and excited-state properties (e.g., absorption spectrum, exciton size).
• Observed pronounced differences in exciton relaxation dynamics across various defect configurations.
• The DV-(5|8|5)-2 defect configuration exhibited the narrowest band gap (1.43 eV), greatest exciton size variation, significant absorption peak intensity contrast, and shortest exciton relaxation time.

Conclusions:

• Defects play a critical role in tuning the electronic and excitonic properties of black phosphorus.
• The DV-(5|8|5)-2 defect configuration demonstrates exceptional potential for advanced optoelectronic applications.
• Findings provide a foundation for the rational design of defect-engineered BP-based materials for solar energy and optoelectronics.